This proposal aims to accomplish the AREA program objectives of 1) supporting meritorious research; 2) exposing undergraduates to research; and 3) strengthening the research environment at non-research intensive universities. The goal of this project is to understand the metabolic activity that supports microbial growth under extreme starvation. In understanding the interactions and processes that sustain microbial communities in starved environments, we hope to better understand one of the outstanding questions of microbial ecology: why are the majority of organisms identified in the environment unculturable in the laboratory? This unculturability is presumed to be due to the inability to reproduce the fastidious growth requirements of many of these species, making them viable within the environment, but unculturable under laboratory conditions. Through this proposal, we aim to test our hypothesis that microbial communities subsist in extremely oligotrophic environments by establishing mutualistic interactions, allowing species to more efficiently utilize the complex nutrient sources entering the system. While such interactions may promote diversity under extreme starvation, obligate mutualism prevents cultivation of these species using traditional techniques. The experiments proposed are geared toward understanding the role that the amount and type of available energy entering these systems have on community diversity and mutualism. The specific aims are: 1) to determine whether microbial mutualistic interactions are occurring under extreme starvation conditions and what role they play in supporting community growth; 2) to determine whether such mutualism increases the usable energy sources and metabolic efficiency under extreme starvation, driving community diversity; and 3) to increase the number of previously unculturable bacterial species from these extremely oligotrophic environments by separating previously interdependent species. By using a combination of techniques to monitor how nutrient flow affects community diversity, we endeavor to understand some of the more complex metabolic interactions capable of supporting life under starvation, while increasing the diversity and number of culturable microbial species. The majority of microbial life on our planet remains unculturable and unknown. Nonetheless, in recent years there has been an upsurge in the number of beneficial products, from pharmaceuticals to common household detergents, isolated from these organisms. This proposal aims to understand the mechanisms that support the growth of such microorganisms and increase the number of species that can be successfully isolated. [unreadable] [unreadable] [unreadable]